Effects of polystyrene microplastics on seed germination,growth,and oxidative stress in rice
To examine the effect of microplastics on terrestrial plants,the germination,growth,and oxidative stress of rice exposed to polystyrene microspheres(PS,PSC,PSN)with different surface modifications(original,carboxylated,and aminated)were investigated.The exposure concentrations were 0.2,1,5 mg·L-1,and 30 mg·L-1.Inhibition of the three microplastics on germination rate and seedling root mass were in the order of PSN>PSC>PS,and the suppression of root morphology(root length,root surface area,and root projection area)was generally stronger for the two modified microspheres compared with the original one.Original PS at lower concentrations(0.2 mg·L-1 and 1 mg·L-1)stimulated rice roots to increase defensive activity of the antioxidative system,thereby avoiding oxidative stress.With increasing concentration,the antioxidative ability of roots gradually weakened,which resulted in lipid peroxidation at 30 mg·L-1.However,two surface-modified microplastics led to the inhibition of root antioxidative system at lower concentrations(0.2,1 mg·L-1).PSC induced root oxidative stress at the highest concentration(30 mg·L-1)alone,whereas PSN induced oxidative stress at 1 mg·L-1.With increasing PSN concentration,oxidative stress was further intensified.Eluted substances from the rice root surface increased significantly with increasing microplastic concentration,which may be associated with the antioxidative reaction in the roots.Microplastics of PSC and PSN were observed in root surface eluates at the highest concentration(30 mg·L-1),and the root adsorption may result in oxidative stress and retardation in growth and development.Rice sprout was less sensitive to microplastics than roots,and the sprout weight and chlorophyll content were inhibited to a certain extent.All microplastics led to oxidative stress in sprouts at the highest concentration(30 mg·L-1),whereas the differences between various treatments were not significant.The surface-modified microplastics(particularly PSN)exerted stronger negative impacts on rice seed germination,root growth,and antioxidant system compared with the original PS.
国家科技期刊平台
NSTL
万方数据
维普
